A wig, especially one to be fitted on a head will be used everyday and, therefore, will deteriorate with time.
Because a popular wig that is manufactured by manual implantation has a very high price of hundreds of thousands of yen, it would in most cases be kept using, even if it has somewhat deteriorated with time such as having been color-faded and weakened. The deteriorated wig would be more easily found out, which should give more reluctance to wearing the wig, for a user who may even feel an inferior complex to wearing a wig,
As a consequence, a disposable wig that has been proposed and produced on a commercial basis after many years' labor wins popularity not only in our country but also in foreign countries.
An example of this disposable type wig is disclosed in Japanese Patent No. 4009910. A wig 30 according to Patent Document 1 has a structure such as shown in FIG. 20(A), wherein a root portion 35 of a hair material 31 greatly juts out from one side of an ultra-thin base 33, the inside of the root portion 35 is secured to the base 33 by means of an adhesive 34 comprising a UV curing agent filled therebetween, which is covered by a sticky layer 37.
The sticky layer 37 comprises a sticky agent having properties of relatively strong adhesion and hardness, which will be prevented from accidental removal when being fitted to the skin.
Furthermore, as shown in FIG. 20(B), the structure is such that the concaves 38 and the convexes 39 formed between the root portions 35 and other portions will turn reversal with each other, when fitted to the skin 20, in order to prevent shining of the base due to irregular light reflection such as shown by arrows and also to prevent removal of the hair materials due to pressure F toward the base. However, this should result in the fact that the sticky layer is bonded to the skin 20 exactly only at the spots S (see FIG. 18). Although it is shown in FIG. 20(B) that the sticky layer 37 appears to have planar contact with the skin 20, the sticky layer 37 is bonded to the skin 20 at points S, because the skin 20 has slight unevenness in a microscopic viewpoint, as shown in FIG. 18.
Furthermore, when removed after being fitted, as shown in FIG. 21, a considerable number of stratum corneum 21 should be separated from the skin 20, because of strong adhesive force.
To prevent removal of the stratum corneum 21, it would be effective to use a sticky agent having relatively weak adhesion (herein later referred to by “weak sticking agent”), and the present inventors have tried to do so. However, it has been proved that this cannot solve the problem, because when the weak sticking agent is laid upon a sticky agent having relatively strong adhesion (hereinlater referred to by “strong sticking agent”), the adhesion of the weak sticking agent becomes stronger.
With respect to the spotty bonding, it is expected to solve this problem by creating the planar bonding to the skin 20. In order to achieve the planar bonding, hopefully, there is a relatively thick layer to be interposed between first and second sticky layers so as to absorb the protrusion of the root portions. However, when the interposed layer becomes thicker, the overall thickness of the wig also becomes greater, so that the receding hairline looks like a wig indeed, which provides a disadvantage of extremely decreasing the appearance.
Moreover, in a case of the strong sticky agent, there is a disadvantage that it is substantially impossible to eliminate the stratum corneum 21 adhered to the sticking surface of the sticking layer that has been separated.
Furthermore, in a wig using the strong sticky agent, there is a risk that the said strong sticky agent could remain on the skin 20. In addition, when the wig is fitted by a user him- or herself, the base tends to shrink due to strong sticky force of the sticky agent, which will in some case make it difficult to fit the wig well onto a desired site.
As described above, the wig has a restriction due to product thickness and, therefore, has inconsistent relationship between the sticky force and the planar bonding.